This section provides background information related to the present disclosure which is not necessarily prior art.
Supermarket refrigeration systems may include low temperature refrigeration cases and medium temperature refrigeration cases. Refrigeration cases are cooled by evaporators that discharge low pressure refrigerant vapor to respective compressors. Medium temperature evaporators discharge an intermediate pressure refrigerant to a medium temperature compressor and the medium temperature compressor discharges a high pressure refrigerant. Low temperature evaporators discharge a low pressure refrigerant to a low temperature compressor and the low temperature compressor discharges a high pressure refrigerant. Thus, the low temperature compressor operates with a relatively high compression ratio because it needs to bring the refrigerant to a condensing pressure.
Compressors may lubricated by oil, which is circulated to various compressor components. When a compressor operates, small amounts of oil may be pumped out of the compressor along with the compressed refrigerant. Too much oil flow through the refrigeration system (e.g., condenser, evaporator) may interfere with efficient operation of the refrigeration system. Thus, compressors may include oil separators to remove oil from refrigerant. The oil separator may return the oil to the compressor as needed while allowing the refrigerant to flow through the refrigeration system.